1下列等式错误的是()Asin(AB)sin(AB)2sinAcosB Bsin(AB)sin(AB)2cosAsinBCcos(AB)cos(AB)2cosAcosB Dcos(AB)cos(AB)2sinAcosB2sin15sin75()A.B. C. D13sin105sin15等于()A. B. C. D.4sin37.5cos7.5_.1sin70cos20sin10sin50的值为()A. B. C. D.2cos72cos36的值为()A32 B. C D323在ABC中,若sinAsinBcos2,则ABC是()A等边三角形 B等腰